Various configurations of steam turbine systems are known. They include a steam turbine that is divided into multiple turbine stages. It is thus possible for example for a high-pressure stage, an intermediate pressure stage and a low-pressure stage to be provided. During operation of the steam turbine system, steam produced in the steam generator is supplied to the steam turbine, where it is expanded. This converts thermal energy into mechanical energy that is used to drive a consumer such as a generator.
The demands on steam turbine systems with regard to shorter and gentler start-up times during a hot start are ever-increasing. Normally, the steam turbine is charged with steam generated in the steam generator only once the steam has been heated to a temperature above that of the hottest turbine stage. Since, after a shutdown of the steam turbine system, the steam generated generally cools down faster than the respective turbine stages, this procedure lasts multiple minutes, leading to undesirably long delay times.
One known possibility for reducing this delay time consists in starting up the steam turbine system even when the steam temperature is still below that of the hottest turbine stage. This is in principle permissible if the steam temperature is raised rapidly enough. However, a consequence of this start-up method is a reduction in the service life of the steam turbine, which is to be avoided.